This invention relates to novel copolymers incorporating a triorganotin moiety. This invention further relates to tin-containing polymers which retain efficacious levels of biological activity over a longer period of time relative to prior art materials.
The biological activity of polymers containing at least one triorganotin moiety (R.sub.3 Sn--) is well known. U.S. Pat. No. 3,167,473 discloses polymers obtained by polymerizing triorganotin derivatives of ethylenically unsaturated acids, including acrylic, methacrylic, and vinyl-benzoic acids. The resultant products are employed as the toxicant in antifouling marine coatings and in compositions applied to agricultural food crops for the purposes of protecting them against infestation by a variety of harmful organisms, particularly fungi.
It has now been found that the biological activity of a given organotin-containing polymer, particularly when exposed to water, is strongly influenced by the extent to which the polymer swells as the triorganotin radicals (R.sub.3 Sn--) are gradually removed by hydrolysis. Specifically, superior results are obtained if the copolymer incorporates a moiety with a functionality of 3 or more, such as a residue derived from 1,3-butane diol glycol dimethacrylate, ethylene glycol dimethacrylate, or divinyl benzene.